Analysis of immune system in Mycobacterium tuberculosis-infected lung and vaccine development.

在这项研究中，我们分析了结核分枝杆菌ag特异性CD4^+ T细胞在结核分枝杆菌（Mtb）感染小鼠肺部的反应动力学。为了检测分枝杆菌Ag85B特异性T细胞，我们使用转基因小鼠（P25-TCR Tg小鼠）表达来自分枝杆菌Ag85B特异性CD4^+ T细胞的T细胞受体（TCR）。在第一个系列实验中，我们将转基因CD4^+ T细胞转移到野生型小鼠体内，然后气管内感染Mtb。虽然转移的转基因T细胞对Ag分枝杆菌具有特异性，但我们未能在mtb感染的肺及其引流淋巴结中检测到转基因T细胞的明确Th1反应。我们假设在肺中未检测到转移的转基因T细胞，因为肺中的T细胞反应比其他部位延迟，并且在分析过程中转移的T细胞未能增殖。这可能导致转移的T细胞被胸腺新迁移的T细胞稀释。为了解决这种可能性，我们接下来感染了P25-TCR Tg小鼠本身。在结核分枝杆菌感染后2周以上，肺引流淋巴结和肺浸润细胞中未检测到转基因CD4^+ T细胞的th1型免疫应答。在感染早期，表达ag85b的减毒细菌M.bovis BCG也未能在P25-TCR Tg小鼠的肺部诱导Th1反应。另一方面，卡介苗皮下感染在接种后第3天诱导了腹股沟和腘窝引流淋巴结的Th1应答。这表明P25-TCR Tg小鼠可以在肺外迅速对Ag85B产生Th1型免疫反应。所有结果表明，针对结核分枝杆菌的保护性免疫反应在肺部延迟。这可能支持肺结核的建立，特别是当肺免疫系统没有诱导保护性免疫反应时。虽然肺免疫反应迟缓的机制尚未明确，但有关机制的进一步信息可能有助于开发针对肺的新疫苗，以诱导对肺结核的保护性免疫。少

In this research, we analyzed kinetics of mycobacterial Ag-specific CD4^+ T cells response in the Mycobacterium tuberculosis-(Mtb)-infected lung of mice. To detect mycobacterial Ag-specific T cells, we used transgenic mice (P25-TCR Tg mice) expressing T cell receptor (TCR) from CD4^+ T cells specific for mycobacterial Ag85B. In the first series of experiments, we transferred the transgenic CD4^+ T cells into wild type mice, then intratracheally infected the mice with Mtb. Although the transferred transgenic T cells were specific to mycobacterial Ag, we failed to detect clear Th1 response of the transgenic T cells in the Mtb-infected lung and its draining lymph nodes. We hypothesized that transferred transgenic T cells were not detected in the lung because T cell response in the lung delays compared to other sites, and transferred T cells failed to proliferate during the analysis. This may be resulted in dilution of transferred T cells by newly emigrated T cells from thymus during the a … More ssay. To address the possibility, we next infected P25-TCR Tg mice themselves. Th1-type immune response of the transgenic CD4^+ T cells was not detected in the lung draining lymph nodes and the lung infiltrating cells until more than 2 weeks after Mtb lung infection. Ag85B-expressing attenuated bacteria, M.bovis BCG, also failed to induce Th1 response in the lung of P25-TCR Tg mice at early stage of infection. On the other hand, subcutaneous infection of BCG induced Th1 response in the draining inguinal and popliteal lymph nodes from day 3 after inoculation. This demonstrates that P25-TCR Tg mice can develop Th1 type immune response to Ag85B quickly outside the lung. All the results suggest that protective immune response against Mtb delays in the lung. This may support establishment of pulmonary tuberculosis especially when protective immune response is not induced in the lung immune system. Although the mechanism of the retardation of lung immune response is not yet clearly identified, further information on the mechanism may support development of new vaccine targeted to the lung to induce protective immunity against pulmonary tuberculosis. Less